Rails - Nested form - 2 levels

Question

I want to build a form following this idea:

• I have Assignment, Activity, Task, AssignmentActivity, ActivityTask and AssignmentActivityTask models

• 1 assignment has many activities and 1 activity has many tasks

  • (there's a many-to-many relation between:
    
    • Assignment - Activity
    • AssignmentActivity - Task,
  • and a One-to-many relation:
    • Activity - Task)

I've made the Assignment-Activity form using this idea: http://railscasts.com/episodes/17-habtm-checkboxes

and the form looks like this

_form.html.erb

<% form_for @assignment do |f|%>
  <% Activity.all.each do |a|%>
    <% check_box_tag "assignment[activity_ids][]", a.id,  @assignment.activity_ids.include?(a.id)%> | <% a.name%>
  <%end%>
<%end%>

So it saves inside the assignment, all the activities that I've checked.

The problem comes when I tried to add the ability to save task inside this form. This is what I've tried

_form.html.erb

<% form_for @assignment do |f|%>
  <% Activity.all.each do |a|%>
    <%= check_box_tag "assignment[activity_ids][]", a.id,  @assignment.activity_ids.include?(a.id)%> | <% a.name%> <br>
    <% a.tasks.each do |t|%>
      #THIS
      <% check_box_tag "assignment[activity_ids][][]", t.id, "Something here"%><br>
    <%end%>
  <%end%>
<%end%>

But I'm not sure how to write the line after the comment.

So when it saves it should save inside the assignment the activities and also the tasks

Is there a way of doing this?

Thanks in advance

Javier QQ

Answer 1

You can try to pass the assignment id as a params and use a Helper Method to save the objects in the multiple models. In ActionView::Helpers API you have something like this:

check_box(object_name, method, options = {}, checked_value = "1", unchecked_value = "0")

So maybe try something like this in your block of code:

<% check_box_tag "assignment[activity_ids][][]", propagate(t.id)%>

And in your AssignmentHelper.rb, try to implement a method called propagate:

def propagate(id)
  *Fetch the id of Activity
  *Fetch the id of Task
  *Save both objects 
end

Hope this helps.

Answer 2

I'd recommend nested_forms by ryanb. It'll take care of what you're wanting to do really well and very quickly.

Answer 3

You don't need to use any external libraries because Rails handles nested forms just fine.

Become comfortable with using fields_for and your problems will be sorted.